Apparatus for maintaining a constant tension in a moving filament



Aug. 25, 1953 H. GREIN APPARATUS FOR MAINTAINING A CONSTANT TENSION IN A MOVING FILAMENT Filed Sept.

INVENTOR. HERMAN QRE/I) BY '1 0' f1 I f 4 7 Patented Aug. 25, 1953 APPARATUS FOR MAINTAINING A CON- STANT TENSION IN A MOVING FILA- MENT Hermann Grein, Remscheid-Lennep, Germany,

assignor to Barmer Maschinenfabrik Aktiengesellschaft, Wuppertal-Oberbarmen, Germany Application September 5, 1951, Serial No. 245,130 In Germany September 18, 1950 13 Claims.

The present invention relates to an apparatus for maintaining a constant tension in a moving filament.

It is not uncommon in the manufacture of textile filaments for these filaments to pass over elements which produce different frictions on the moving filament or for the moving filaments to be drawn with varying forces so as to produce varying tensions in these filaments. If no measures are taken to avoid these variations in the tensions, an inferior product is produced, characterized by hard portions and soft portions, which results in various difiiculties in the further use of the filaments.

One of the objects of the present invention is to overcome the above defects by providing. a device and process which will ensure the maintenance of a constant tension in a moving filament.

A further object of the present invention is to provide a device which is sensitive to the moving filament itself in order to maintain the tension therein constant.

Another object of the present invention is to provide a process and apparatus for adjusting the tension produced on the moving filament so that a tension of a particular magnitud which is most suitable for a particular filament may be obtained with a single device.

Still a further object of the present invention is to provide a device of the above type which is of an exceedingly simple construction and exceedingly reliable in operation.

Yet another object of the present invention is to provide a device of the above type which may be easily and conveniently cleaned.

With the above objects in view, the present invention mainly consists in an apparatus and process for maintaining a constant tension in a moving filament, and in this apparatus and process there is a support member upon which a bearing member is fixedly mounted. This bearing member is formed with an elongated bore and has a stop member threadedly mounted thereon adjacent to the bore so that the stop member may be adjusted on the bearing member. An elongated shaft is mounted in the bore of the bearing member for axial movement therein, the shaft being threaded along a portion thereof. A

pin member extends through the shaft at one stop member permits the predetermined position of the shaft in the bearing to be changed. Connected to the opposite end of the shaft is a first dish-shaped member, which is fixedly joined to the shaft at the central part of a fiat base portion of this dish-member. A magnet having a threaded bore is threadedly mounted on the threaded portion of the shaft so as to be adjustably movable towards and away from the first dish member. A circular member is fixed to the magnet and has a plurality of equally spaced notches formed in the periphery thereof. These notches are adapted to be engaged by a resilient elongated member fixed to the support so as to releasably hold th magnet in a predetermined position on the shaft. There are also mounted on the support a pair of lugs each of which has a slot formed therein. A second dish-shaped member having a fiat base portion located next to the fiat base portion of the first dish-shaped member is provided with a projection which is pivotally mounted in the slots of the lugs so that the second dish-shaped member may be moved angularly with respect to the first dishshaped member. This second dish-shaped member is made of a magnetic material so that it is attracted by the magnet toward the first dishshaped member. A guide member for guiding the filament is located on the same side of the first dish-shaped member as the second dishshaped member but at a further distance from the first dish-shaped member than the second dish-shaped member. In this way, when a filament is guided between the fiat base portions of the first and second dish-shaped members and around the guide member, the direction of movement of the filament will be changed after it leaves the dish-shaped members. When the tension in the filament tends to increase, it will move the second dish-shaped member angularly away from the first dish-shaped member against the action of the magnet, and in this way the friction produced on the filament by the dishshaped members isautomatically maintainin constant.

In the specification and claims, the term filament is intended to include all textile threads which are made up of one or a plurality of fibers. These filaments may be of any natural materials or of synthetic plastic materials, for example.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. Th invention itself, however, both as to its construction and its method of operation, together with addi- 3 tional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. 1 is an elevational, partly schematic view of one possible embodiment of an apparatus for carrying out the present invention;

Fig. 2 is a plan view of the structure illustrated in Fig. 1;

Fig. 3 is a view of the structure of Fig. 1 in a different position thereof;

Fig. 4 is an elevational view of a detail of the structure illustrated in the other figures; and

Fig. 5 is a fragmentary sectional view taken along line 5--5 of Figure 3 in the direction of the arrows.

Referring to the drawings, there is shown a support member 20 upon which the bearing member I is fixedly mounted. This bearing member 1 is formed with a bore 2I extending therethrough and has threadedly mounted thereon the adjustable stop member 8. The shaft 6, which is threaded at the right-hand portion thereof, as viewed in the drawings, is mounted with the smooth left-hand portion thereof, as viewed in the drawings, in the bore 2I of bearing member I for axial movement therein. The pin member 22 extends through the shaft 6 and has the spring 9 fixedly connected thereto, this spring 9 extending into a bore of member I and being fixedly connected to a pin in this bore of bearing member 1, as is illustrated in Fig. 5. The pin member 22 bears against the stop member 8, so that when the shaft 6 is drawn to the left, as viewed in the drawings,

for a purpose to be described below, the spring member 9 will automatically return the shaft 6 to its original position.

The shaft 6 has fixedly mounted on the righthand thereof, as viewed in the drawings, a dishshaped member 2, and, as is apparent from the drawings, this dish-shaped member 2 has a fiat base portion which is fixedly joined to the shaft 6. Although this member 2 may be made of a magnetic material, it is preferred that it be made of a nonmagnetic material.

A magnet 4 having a threaded bore is mounted on the threaded-portion of shaft 6 and threadedly engages the same, magnet 4 being connected to shaft 6 before member 2 is fixed thereto. This magnet 4 is fixedly connected to the circular member 5 by any suitable means, such as riveting or welding, for example, and this circular member 5 has a peripheral flange 23 formed has an edge portion 26 adapted to engage one of the notches 24 of the circular member 5. By means of this construction the magnet 4 is releasably held on the shaft 6 in an adjusted position. The magnet 4 may be turned against the action of springy member 25, but the latter, by engagement with a notch 24, will be capable of holding the magnet 4 in a predetermined position on the shaft 6, and magnet 4 together with spring 9 prevent undesirable rotation of shaft 6.

Fixedly supported on the support 20 are a pair of lugs 21, which may be ears formed integrally with the material 28 and bent therefrom, as shown in Fig. 2. This material 28, which may be metal, for example, is fixedly mounted on a side extension 29 of the support 20 by any suitable means, such as riveting or welding. Each of the lugs 21 is formed adjacent its left end. as viewed in the drawings, with a slot 30.

A second dish-shaped member I is provided with a flat base portion located next to the flat base portion of dish-shaped member 2. This dish-shaped member I, which is shown as viewed from the rear in Fig. 4, has a lower extension 3| formed integrally therewith and carrying a pair of projections 32 which respectively engage.

. that it is attracted toward the dish-shaped member 2 by the magnet 4, and it is believed evident that the dish-shaped member I will be urged towards the dish-shaped member 2 with a force which varies inversely with the distance of the dish-shaped member I from dish-shaped member 2, so that the magnet .4 exerts a greater force on dish-shaped member I in the position thereof illustrated in Fig. 1 than in the position thereof illustrated in Fig. 3, for example.

A guide member II, for guiding the filament I 0 after it leaves the dish-shaped members I and 2, is schematically illustrated in Figs. 1 and 3 of the drawings, and it will be noted that this guide member I I is located on'the same side of the dish-shaped member 2 as the dish-shaped member I but at a greater distance from the dish-shaped member 2 than the dish-shaped member I.

As a result of the above construction, when the filament I0 is guided through the fiat base portions of the dish-shaped members I and 2, the magnet 4 will produce a predetermined tension on the filament III by attracting the dish-shaped member I toward the dish-shaped member 2 so that the filament is contacted by the fiat base portions of the dish-shaped members I and 2- with a predetermined friction. As is evident from Fig. 1, the pathof movement of the filament I0 is changed after it leaves the dish-shaped members I and 2 as a result of the location of guide member I I with respect to the-other parts of the device. As a result of this arrangement, the moving filament itself will constantly be urging the dish-shaped member I about the axis 3 away from the dish-shaped member2. I Thus, if the tension in the filament I0 should tend to rise above a predetermined limit, the filament III will then turn the dish-shaped member I about the axis ,3 from the position shown in Fig. l to that shown in Fig. 3, for example, so that in this way the friction of the dish-shaped member 2 against the filament III is materially reduced and the force of the dish-shaped member I magnet 4 may be located at a desired distance from the dish-shaped member 2 by the abovedescribed construction so as to adjust the size of the air gap between the magnet 4 and the dishshaped member I and in this way controlthe tension which is produced in the filament by the device.

Due to the passing of the filament l0 through the flat base portion of the dish-shaped members I and 2, it may happen that small fiber particles may accumulate on these fiat base portions after a period of time, and therefore it is desirable to clean these fiat portions periodically. In order to do this, it is only necessary to move the shaft 6 against the action of spring 9 to the left, as viewed in the drawings, and in this way the fiat base portions of the dish-shaped members are separated so that they may be easily and conveniently cleaned. The shaft 6 is then simply released to the action of spring 9 so that it is automatically returned to its original position by the cooperation of the adjustably mounted stop 8 and the pin member 22.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of apparatus and process for maintaining a constant tension in a moving filament differing from the types described above.

While the invention has been illustrated and described as embodied in a device sensitive to a 1 moving filament for maintaininga constant tension in the same, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. Apparatus for automatically maintaining a constant tension in a moving filament, comprising in combination, a pair of members each of which has a substantially flat surface portion facing the substantially fiat surface portion of the other member and being located closely adjacent thereto, said substantially fiat surface portions being respectively located on opposite sides of a plane passing therebetween and one of said members bein mounted, at at least a part of said fiat surface portion thereof, for movement toward and away from the other of said members; moving means associated with said one of said members for urging the same toward the other of said members with a force which varies inversely with the distance of said part of said fiat surface portion of said one member from said other member so that said fiat surface portions contact and produce a tension in a filament moving in said plane and located between said fiat surface portions; and guide means, for guiding the filament, being associated with said members and located on the same side of said plane as said one member but at a further distance from said plane than said 'fiat surface portion of said one member so as to change the direction of movement of a filament when it leaves said member, whereby, when the'tension in the filament moving between and contacting said fiat surface portions of said members tends to increase, the filament moves said part of said fiat surface portion of said one member away from said other member against the action of said 'moving means so as to decrease the length of filament contacted by the fiat-surface portion of said other member and decrease the force of said flat surface portion of said one member against said'filament, to thereby automatically maintain the tension constant.

2. Apparatus for maintaining a constant ten-- sion in a moving filament, comprising in combination, a first member having a substantially fiat surface portion; a second member made of a ma netic material and having a substantially flat surface portion located next to said fiat surface portion of said first member, said second member being pivotally mounted so that said flat surface portion thereof is angularly movable toward and away from said fiat surface portion of said first member, said fiat surface portions of said first and second members being respectively located on opposite sides of a plane passing between said fiat surface portions; magnetic means associated with said second member for urging the fiat surface portion thereof toward said fiat surface portion of said first member; and guide means, for guiding a filament, being associated with said members and located on the same side of said plane as said second member but at a further distance from said plane than said fiat surface portion of said second member so as to change the direction of a moving filament after the latter leaves said members, whereby a filament passing between said fiat surface portions of said memhers is contacted by the same so that a tension is produced in the filament, and whereby, when the tension in the filament tends to increase, the filament pivots said fiat surface portion of said second member away from said first member so as to decrease the length of contact of the filament with the fiat surface portion of said first member so as to thereby maintain a constant tension in the filament.

3. Apparatus for maintaining a constant tension in a moving filament, comprising in combination, a first member having a substantially fiat surface portion; a second member made of a magnetic material and having a substantially fiat surface portion located next to said fiat surface portion of said first member, said second member being pivotally mounted so that said flat surface portion thereof is angularly movable toward and away from said fiat surface portion of said first member, said fiat surface portions of said first and second portions being respectively located on opposite sides of a plane passing between said fiat surface portions; magnetic means located on the same side of said plane as said first member and being associated with said second member for attracting the flat surface portion thereof toward said fiat surface portion of said first member with a force which varies inversely with the distance of said fiat surface portion of said second member from said fiat surface portion of said first member; and guide means, for guiding a filament, being associated with said members and located on the same side of said plane as said second member but at a further distance from said plane than said fiat surface portion of said second member so as to change the direction of a movingfilament after the latter leaves said members,

7 whereby a filament passing between said fiat surface portions of said members is contacted by the same so that a tension is produced in the filament, and whereby, when the tension in the filament tends-to increase, the filament pivots said flat surface portion of said second member away from said first member so as to decrease the length of contact of the filament with the fiat surface portion of said first member and decrease the force of said surface portion of said second member bearing against the filament so as to thereby maintain a constant tension in the filament.

4. Apparatus for maintaining a constanttension in a moving filament, comprising in combination, a first member having a substantially fiat surface portion; a second member made of a magnetic material and having a substantially fiat surface portion located next to said fiat surface portion of said first member, said second member being pivotally mounted so that said fiat surface portion thereof is angularly movable toward and away from said fiat surface portion of said first member, said fiat surface portions of said first and second portions being respectively located on opposite sides of a plane passing between said fiat surface portions; magnetic means located on the same side of said plane as said first member and being associated with said second member for attracting the fiat surface portion thereof toward said fiat surface portion of said first member with a force which varies inversely with the distance of said'fiat surface portion of said second member from said fiat surface portion of said first member; guide means, for guiding a filament, being associated with said members and located on the same side of said plane as said second member but at a further distance from said plane than said flat surface portion of said second member so as to change the direction of a moving filament after the latter leaves said members, whereby a filament passing between said fiat surface portions of said members is contacted by the same so that a tension is produced in the filament, and whereby, when the tension in the filament tends to increase, the filament pivots said fiat surface portion of said second member away from said first member so as to decrease the length of contact of the filamentwith the fiat surface portion of said first member and decrease the force of said surface portion of said second member bearing against the filament so as to thereby maintain a constant tension in the filament; and mounting means mounting said first member for movement away from said second member so as to permit the fiat surface portions of said members to be cleaned.

5. Apparatus formaintaining a constant tension in a moving filament, comprising in combination, a first member having a fiat surface portion; a second member having a fiat surface portion located next to said flat surface portion of said first member and on one side of said first member, said second member being made of a magnetic material and being mounted for pivotal movement about an edge portion thereof toward and away from said first member; a magnet 10- cated on the side of said first member opposite from said second member for urging said fiat surface portion of said second member toward said flat surface portion of said first member so that flat surface portions contact a filament passing between the same to produce a tension therein; and guide means located on the same side of said first member as said second member but at a further distance from said first member than said second member so as to change the direction of movement of a filament when it leaves said members, whereby, when the tension in a filament moving between said fiat surface portions of said members tends to increase, the filament turns said second member about said edge portion thereof away from said first member and against the action of said magnet so as to thereby decrease the tension produced in said filament and thereby automatically maintain a constant tension in the filament.

6. Apparatus for maintaining a constant tension in a movingfilament, comprising in com bination, a first member having a flat surface portion; a second member having a flat surface portion located next to said fiat surface portion of said first member and on one side of said first member, said second member being made of a magnetic material and being mounted for pivotal movement about an edge portion thereof toward and away from said first member; a magnet located on the side of said first member opposite I from said second member for urging said fiat surface portion of said second member toward said fiat surface portion of said first member so that fiat surface portionscontact a filament passing between the same to produce a tension therein, said magnet being adjustably mounted for movement toward and away from said first member so as to adjust the force of attraction of said magnet on said second member; and guide means located on the same side of said first member as said second member but at a further distance from said first member than said second member so as to change the direction of movement of a filament when it leaves said members, whereby, when the tension in a filament moving between said fiat surface portions of said members tends to increase, the

- filament turns said secondmember about said edge portion thereof away from said first member and against the action of said magnet so as to thereby decrease the tension produced in said filament and thereby automatically maintain a constant tension in the filament.

'7. Apparatus for maintaining a constant tension in a moving filament, comprising in combination, a first member having a'fiat surface portion; a second member having a fiat surface portion located next to said fiat surface portion of said first member and on one side of said first member, said second member being made of a magnetic material and being mounted for pivotal movement about an edge portion thereof toward and away from said first member; a magnet located on the side of said first member opposite from said second member for urging said fiat surface portion of said second member toward said fiat surface portion of said first member so that fiat surface portions contact a filament passing between the same to produce a tension therein, said magnet. being. adjustably mounted for movement toward and away from said first member so as to adjust the force of attraction of said magnet on said second member; guide means located on the same side of said first member as said second member but at a further distance from said first member than said second member so as to change the direction of movement of a filament when it leaves said members, whereby, when the tension in a filament moving between said flat surface portions of said members tends to increase, the filament turns said'second member about said means mounting saidfirst member for movement away from said second member so that said flat surface portions of said members may be cleaned.

8. Apparatus for maintaining constant tension in a moving filament, comprising in combination, a support member; bearing means mounted on said support member; shaft means supported for axial movement in said bearing means; a first dish-shaped member having a fiat base portion fixedly connected to said shaft means at one end thereof; a second dish-shaped member made of magnetic material and having a fiat base portion located next to said fiat base portion of said first dish-shaped member, said second dishshaped member being mounted on said support member for pivotal movement about an axis substantially perpendicular to the axis of said shaft means; magnet means mounted on said shaft means for attracting said second member toward said first member so that the base portions of said members contact a filament passing therebetween to produce a tension therein; and guide means located on the same side of said first member as said second member but at a greater distance from said first member than said second member for guiding a filament and changing the direction of movement thereof after it leaves said members, whereby, when the tension in the filament tends to increase, the filament turns said second member away from said first member so as to decrease the tension produced in said filament by said members and thereby automatically maintain a constant tension in the filament.

9. Apparatus for 'maintaining constant tension in a moving filament, comprising in combination, a support member; bearing means mounted on said support member; shaft means supported for axial movement in said bearing means; a first dish-shapedmember having a fiat base portion fixedly connected to said shaft means at one end thereof; a second dish-shaped member made of magnetic material and having a fiat base portion located next to said fiat base portion of said first dish-shaped member, said second dish-shaped member beingmounted on said support member for pivotal movement about an axis substantially perpendicular to the axis of said shaft means; magnet means mounted on said shaft means for attracting said second member toward said first member so that the base portions of said members contact a filament passing therebetween to produce a tension therein, said magnet means being mounted for movement along said shaft means so as to adjust the force with which said magnet means urges said second member toward said first member; and guide means located on the same side of said first member as said second member but at a greater distance from said first member than said second member for guiding a filament and changing the direction of movement thereof after it leaves said members, whereby, when the tension in the filament tends to increase, the filament turns said second member away from said first member so as to decrease the tension produced in said filament by said members and thereby automatically maintain a constant tension in the filament.

10. Apparatus for maintaining constant tenbination, a support member; bearing mea mounted on said support member; shaft meaiis supported for axial movement in said bearing means; a first dish-shaped member having afiat base portion fixedly connected to said shaft means at one end thereof; a second dish-shaped member made of magnetic material and having a fiat base portion located next to said fiat base portion of said first dish-shaped member, said second dish-shaped member being mounted on said support member for pivotal movement about an axis substantially perpendicular to the axis of said shaft means; magnet means mounted on said shaft means for attracting said second member toward said first member so that the base portions of said members contact a filament passing therebetween to produce a tension therein, said magnet means being mounted for movement along said shaft means so as to adjust the force with which said magnet means urges said second member toward said first member; guide means located on the same side of said first member as said second member but at a greater distance from said first member than said second member for guiding a filament and changing the direction of movement thereof after it leaves said members, whereby, when the tension in the filament tends to increase, the filament turns said second member away from said first member so as to decrease the tension produced in said filament by said members and thereby automatically maintain a constant tension in the filament; and releasable holding means mounted on said support and engaging said magnet means for releasably holding the latter at a predetermined position on said shaft.

11. Apparatus for maintaining constant tension in a moving filament, comprising in combination, a support member; bearing means mounted on said support member; shaft means supported for axial movement in said bearing means; stop means mounted on said bearing means; spring means operatively connected to said shaft means for urging the same in one direction in said bearing means and against the stop means; a first dish-shaped member having a fiat base portion fixedly connected to said shaft means at one end thereof; a second dish-shaped member made of magnetic material and having a flat base portion located next to said fiat base portion of said first dish-shaped member, said second dish-shaped member being mounted on said support member for pivotal movement about an axis substantially perpendicular to the axis of said shaft means, said shaft means and said first dish-shaped member being movable in said bearing means against the action of said spring means so that the fiat base portions of said members may be cleaned, said stop means guaranteeing that the first dish-shaped member will be returned to its original position after cleaning thereof; magnet means mounted on said shaft means for attracting said second member to Ward said first member so that the base portions of said members contact a filament passing therebetween to produce a tension therein; and guide means located on the same side of said first member as said second member but at a greater distance from said first member than said second member for guiding a filament and changing the direction of movement thereof after it leaves said members, whereby, when the tension in the filament tends to increase, the filament turns said second member away from said first tomatically maintain a constant tension in the' filament.

12. Apparatus for maintaining constant tension in a moving filament, comprising in combination, a support member; bearing means mounted on said support member; shaft means supported for axial movement in said bearing means; stop means mounted on said bearing means; spring means operatively connected to said shaft means for urging the same in one direction in said bearing means and against said stop means; a first dish-shaped member having a fiat base portion fixedly connected to said shaft means at one end thereof; asecond dish-shaped member made of magnetic material and having a fiat base portion located next to said fiat base portion of said first dish-shaped member, said second dish-shaped member being mounted on said support member for pivotal movement about an axis substantially perpendicular to the axis of said shaft means, said shaft means and said first dish-shaped member being movable in said bearing means against the action of said spring means so that the fiat base portions of said members may be cleaned, said stop means guaranteeing that the first dish-shapedmember will be returned to its original position after cleaning thereof; magnet means mounted on said shaft means for attracting said second member toward said first member so that the base portions of said members contact a filament passing therebetween to produce a tension therein, said magnet means being mounted for movement along said shaft means so as to adjust the force with which said magnet means urges said second member toward said first member; guide means located on the sameside of said first member as said second member but at a greater distance from said first member than said second member for guiding a filament and changing the direction ofmovement thereof after it leaves said members, whereby, when the tension in the filament tends to increase, the filament turns said second member away from said first member so as to decrease the tension produced in said filament by said members and thereby automatically maintain a constant tension in the filament; and releasable holding means mounted on said support and engaging said magnet means for releasably holding the latter at a predetermined position on said shaft.

13. Apparatus for maintaining a constant tension in a moving filament, comprising in combination, a support member; a bearing member fixedly connected to said support member and being formed with an elongated bore passing therethrough; a stop member threadedly mounted on said bearing member adjacent an end of 12 said bore so that saidstop member may be ad- Justed on said bearing member; an elongated shaft mounted in said bore of said bearing member for axial movement therein, said shaft being threaded along a portion thereof; a pin member extending through said shaft at one end thereof and overlapping. said stop member; spring means interconnecting said pin member with said bearing member for urging said pin member against said stop member so as to releasably maintain said shaft at a predetermined position in said bearing, the adjustable mounting of said stop member permitting said predetermined position of said shaft in said bearing to be changed; a first dish-shaped member having a fiat base portion fixedly connected at a central part thereof to the other end of said shaft; a magnet having a threaded bore and being mounted on said shaft with said bore of said magnet engaging said threaded portion of said shaft so that said magnet is mounted for movement along said shaft toward and away from said first dish-shaped member; a circular member fixed to said magnet, extending therearound and having a plurality of equally spaced notches formed in the periphery thereof; a resilient elongated member fixed to said support and having an edge portion engaging one of said notches of said circular member to releasably hold said magnet in a predetermined position on said shaft; a pair of lugs each fixed at one end thereof to said support member and each being formed with a slot adjacent the other end thereof; a second dish-shaped member having a fiat base portion located next to said fiat base portion of said first dish-shaped member, said second member being of a magnetic material so as to be attracted toward said first dishshaped member and said second member having an extension located between said lugs and including a pair of projections respectively extending through said slots of said lugs so that said second member is mounted for pivotal movement with respect to said first member; and a guide member located on the same side of said first dish-shaped member and said second dishshaped member but at a greater distance from said second member than said first member so as to change the direction of a filament moving between said first and second dish-shaped members.

HERMANN GREIN.

References Cited in the file Of this patent UNITED STATES PATENTS Number Name Date 642,698 Iveson Feb. 6, 1900 1,965,363 Abbott July 3, 1934 2,281,204 Raymond Apr. 28, 1942 2,478,926 Kingsbury Aug. 16, 1949 

